break refinery into refinery_core to remove code duplication

[jxs]

Tried to come up with a way to only have 3 crates (refinery, refinery_cli and refinery_macros) and work on the new features, but can't there are a couple more functions that would be duplicate to be shared by refinery_cli and refinery_macros, therefore the decision to split refinery again into refinery_core

[akhilles]

What about putting the shared functions into a utility crate such as refinery_utils?

In general, I found that having a "shim" crate that mostly re-exports functionality from another crate isn't very ergonomic. You have to keep track of documentation and public/private APIs in 2 different places.

Basically, this is my proposal:
refinery_utils = shared functions
refinery_macros = refinery_utils + proc macros
refinery = refinery_utils + refinery_macros + migrations logic
refinery_cli = refinery_utils + refinery + cli logic

IMO, this allows each crate to have well-defined public API. But, I would also be totally fine with going in the direction of this PR.

[jxs]

What about putting the shared functions into a utility crate such as refinery_utils?

In general, I found that having a "shim" crate that mostly re-exports functionality from another crate isn't very ergonomic. You have to keep track of documentation and public/private APIs in 2 different places.

Basically, this is my proposal:
refinery_utils = shared functions
refinery_macros = refinery_utils + proc macros
refinery = refinery_utils + refinery_macros + migrations logic
refinery_cli = refinery_utils + refinery + cli logic

IMO, this allows each crate to have well-defined public API. But, I would also be totally fine with going in the direction of this PR.

yeah I also agree with that, and I tried it but it started with utils.rs which then requires error::Error which requires AppliedMigration and Migration and following that trail eventually ends up with almost all the code on refinery_utils except the macros, and therefore renaming it to refinery_core and having the shim crate which joins them

[zoechi]

It looks like the tests in refinery_core are not run by circle_ci
and I also can't run them locally.
I get a few errors like

error: couldn't read refinery_core/src/traits/../../tests/sql_migrations/V1-2/V1__initial.sql: No such file or directory (os error 2)
  --> refinery_core/src/traits/mod.rs:95:13
   |
95 |             include_str!("../../tests/sql_migrations/V1-2/V1__initial.sql"),
   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)